The inventive concept relates to a semiconductor memory device, and more particularly, to a 3-dimensional semiconductor memory device.
The degree of integration of semiconductor memory devices has been increased in order to satisfy excellent performance and low price demanded by consumers. In the case of a 2-dimensional or planar semiconductor device, the degree of integration is mainly determined by an area occupied by a unit memory cell, thus being significantly influenced by the level of a fine patterning technique.
However, because super-expensive fabrication equipment is needed for the miniaturization of a pattern, the degrees of integration of 2-dimensional semiconductor devices are increasing, but are still limited. Accordingly, 3-dimensional semiconductor memory devices having 3-dimensionally arranged memory cells have been proposed. In addition, the proposed 3-dimensional semiconductor memory devices need to be fabricated reliably with a high freedom of design.